Proliferation Of Normal Mammary Epithelial Cells Research Articles

Emerging Therapies for Breast Cancer.

The steady, incremental improvements in outcomes for both early-stage and advanced breast cancer patients are, in large part, attributable to the success of novel systemic therapies. In this review, we discuss key conceptual paradigms that have underpinned this success including (1) targeting the driver: the identification and targeting of major oncoproteins in breast cancers; (2) targeting the lineage pathway: inhibition of those pathways that drive normal mammary epithelial cell proliferation that retain importance in cancer; (3) targeting precisely: the application of molecular classifiers to refine therapy selection for specific cancers, and of antibody-drug conjugates to pinpoint tumor and tumor promoting cells for eradication; and (4) exploiting synthetic lethality: leveraging unique vulnerabilities that cancer-specific molecular alterations induce. We describe promising examples of novel therapies that have been discovered within each of these paradigms and suggest how future drug development efforts might benefit from the continued application of these principles.

Abstract P4-07-06: Imipramine Blue - A safe and potent therapeutic regimen that suppresses breast cancer growth and progression by targeting DNA damage surveillance pathway

Abstract Despite improvement in overall survival of breast cancer patients, many women don't survive this disease. Moreover, the quality of life for patients who do survive is often substantially reduced due to the toxicity associated with the chemotherapy. Here, we report that imipramine blue (IB), a novel analogue of anti-depressant imipramine that we recently synthesized, may serve as a safe and potent therapeutic agent for treating breast cancers. We show that IB reduced cell growth, migration and invasion of breast cancer cells. Systemic delivery of IB using nanoparticle-based drug delivery approach suppressed breast cancer growth and metastasis without inducing any toxicity in pre-clinical orthotropic mouse models. Notably, using ex-vivo model of tumor explants from breast cancer patients, we demonstrated that IB inhibited breast cancer growth without affecting normal mammary epithelial cell proliferation. Furthermore, IB improved the sensitivity of breast cancer cells to chemotherapy drugs paclitaxel and doxorubicin. Our results revealed that IB mediated its anti-tumor effect by targeting genes involved in cell cycle progression, microtubule dynamics and DNA damage surveillance pathway including Forkhead Box M1 (FOXM1), stathmin1, S-phase kinase-associated protein 2 (Skp2) and XRCC3, which we show to be highly expressed in breast cancer patients. Importantly, we demonstrated that IB inhibited breast cancer cell's ability to repair DNA strand breaks by impairing homologous recombination events. These findings highlight the potential of IB to be used as a potent therapeutic regimen for treating breast cancer patients. Since IB-1 is derived from a FDA approved drug it has potential to be rapidly translated to the clinic. Citation Format: Rajamanickam S, Subbarayalu P, Timilsina S, Gorthi A, Drake MT, Chen Y, Vadlamudi R, Bishop AJR, Arbiser JL, Rao MK. Imipramine Blue - A safe and potent therapeutic regimen that suppresses breast cancer growth and progression by targeting DNA damage surveillance pathway. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-07-06.

Genistein and erbstatin inhibition of normal mammary epithelial cell proliferation is associated with EGF-receptor down-regulation.

Epidermal growth factor (EGF) is a potent mitogen for normal mouse mammary epithelial cells grown in primary culture. EGF activation of the EGF-receptor (EGF-R) induces intrinsic tyrosine kinase activity which results in EGF-R autophosphorylation and tyrosine phosphorylation of other intracellular substrates involved in EGF-R signal transduction. Genistein and erbstatin are anticancer agents which have been shown to be potent tyrosine kinase inhibitors. However, the effects of these compounds in modulating EGF-dependent normal mammary epithelial cell proliferation is presently unknown. Therefore, studies were conducted to determine the effects of genistein and erbstatin on EGF-dependent proliferation, and EGF-R levels and autophosphorylation in normal mouse mammary epithelial cells grown in primary culture and maintained in serum-free media. Chronic treatment with 6.25-100 microM genistein or 1-16 microM erbstatin significantly decreased EGF-dependent mammary epithelial cell proliferation in a dose-responsive manner. However, the highest doses of genistein (100 microM) and erbstatin (16 microM) were found to be cytotoxic. Additional studies showed that acute treatment with 6.25-400 microM genistein did not affect EGF-R levels or EGF-induced EGF-R autophosphorylation, while acute treatment with 1-64 microM erbstatin caused a slight reduction in EGF-R levels, but had no effect on EGF-dependent EGF-R autophosphorylation in these cells. In contrast, chronic treatment with similar doses of genistein or erbstatin resulted in a large dose-responsive decrease in EGF-R levels, and a corresponding decrease in total cellular EGF-R autophosphorylation intensity. These results demonstrate that the inhibitory effects of chronic genistein and erbstatin treatment on EGF-dependent mammary epithelial cell proliferation is not due to a direct inhibition of EGF-R tyrosine kinase activity, but results primarily from a down-regulation in EGF-R levels and subsequent decrease in mammary epithelial cell mitogenic-responsiveness to EGF stimulation.

Modulation of normal mammary epithelial cell proliferation, morphogenesis, and functional differentiation by retinoids: a comparison of the retinobenzoic acid derivative RE80 with retinoic acid

The ability of retinoids to modulate the proliferation as well as the morphological and functional differentiation of normal mammary epithelial cells isolated from pubescent female virgin rats was evaluated in serum-free primary culture. The retinobenzoic acid derivative RE80, present continuously or for only a limited time in culture, inhibited proliferation with an IC50 of less than 10(-10) M. In contrast, all-trans-retinoic acid (RA) inhibited proliferation with an IC50 of approximately 10(-8) M. In addition to effects on proliferation, RE80 and RA stimulated end bud colonies to differentiate to lobular alveolar colonies, inhibited alveolar budding, and suppressed the outgrowth of squamous colonies. Both retinoids also markedly stimulated functional differentiation, as assessed by accumulation of the major milk protein casein, and stimulated the synthesis of a approximately 73- to 74-kilodalton protein identified as a member of the transferrin family. Moreover, both retinoids stimulated cell death in the differentiated cell population. RE80 was approximately 100-fold more potent than RA for all of these effects. These data suggest that several mechanisms may contribute to the chemopreventive and/or therapeutic efficacy of retinoids in breast cancer, including inhibition of proliferation, stimulation of cell death, and/or induction of differentiation.

Modulation of normal mammary epithelial cell proliferation, morphogenesis, and functional differentiation by retinoids: a comparison of the retinobenzoic acid derivative RE80 with retinoic acid.

The ability of retinoids to modulate the proliferation as well as the morphological and functional differentiation of normal mammary epithelial cells isolated from pubescent female virgin rats was evaluated in serum-free primary culture. The retinobenzoic acid derivative RE80, present continuously or for only a limited time in culture, inhibited proliferation with an IC50 of less than 10(-10) M. In contrast, all-trans-retinoic acid (RA) inhibited proliferation with an IC50 of approximately 10(-8) M. In addition to effects on proliferation, RE80 and RA stimulated end bud colonies to differentiate to lobular alveolar colonies, inhibited alveolar budding, and suppressed the outgrowth of squamous colonies. Both retinoids also markedly stimulated functional differentiation, as assessed by accumulation of the major milk protein casein, and stimulated the synthesis of a approximately 73- to 74-kilodalton protein identified as a member of the transferrin family. Moreover, both retinoids stimulated cell death in the differentiated cell population. RE80 was approximately 100-fold more potent than RA for all of these effects. These data suggest that several mechanisms may contribute to the chemopreventive and/or therapeutic efficacy of retinoids in breast cancer, including inhibition of proliferation, stimulation of cell death, and/or induction of differentiation.